Related Clues:

• Set of rules
• Morse __
• See 21 Across
• Word with bar or zip
• __ of ethics
• Building contractor's study
• Problem for a cracker?
• Morse made one
• Early keyboard instrument
• Hollywood site
• Set of standards
• Programming output
• With 49-Across, where 17-, 24- and 39-Across are seen
• Cryptogram, e.g.
• ZIP ___